android--WebView使用addJavascriptInterface在sdk 17的問題解決

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當調用WebView 的addJavascriptInterface時，使用android:targetSdkVersion="10"時是沒有問題的，能夠觸發事件，但是畢竟使用版本時一般都使用最新的，我在開發時為了追求新，然後使用了android:targetSdkVersion="17"的屬性，開始使用時並沒有什麼問題，大多數手機是可以使用的，比如中興的N986,小米的MIMU4.1的系統是沒有問題的，系統為2.3的幾個機型也沒看出問題，後來三星Note3上出問題啦，調用不了這個事件，我也糾結了半天，後來在網上尋找原因，是去年android的漏洞所致，

所以修改方法有兩個：

1，修改android:targetSdkVersion="10"，這個只能為一時的解決方案，

2. 尋找官方檔案：說在17以上需要添加一個介面JavascriptInterface才能用，後來仔細看了官方的Demo才找到，就是藍色加粗部分。如果這個問題您也遇到過，希望能協助你，謝謝

官方給的說明：

public void addJavascriptInterface (Object object, String name)Added in API level 1

Injects the supplied Java object into this WebView. The object is injected into the JavaScript context of the main frame, using the supplied name. This allows the Java object‘s methods to be accessed from JavaScript. For applications targeted to API level JELLY_BEAN_MR1 and above, only public methods that are annotated with JavascriptInterface can be accessed from JavaScript. For applications targeted to API level JELLY_BEAN or below, all public methods (including the inherited ones) can be accessed, see the important security note below for implications.

Note that injected objects will not appear in JavaScript until the page is next (re)loaded. For example:

 class JsObject {    @JavascriptInterface    public String toString() { return "injectedObject"; } } webView.addJavascriptInterface(new JsObject(), "injectedObject"); webView.loadData("", "text/html", null); webView.loadUrl("javascript:alert(injectedObject.toString())");

IMPORTANT:

• This method can be used to allow JavaScript to control the host application. This is a powerful feature, but also presents a security risk for applications targeted to API level JELLY_BEAN or below, because JavaScript could use reflection to access an injected object‘s public fields. Use of this method in a WebView containing untrusted content could allow an attacker to manipulate the host application in unintended ways, executing Java code with the permissions of the host application. Use extreme care when using this method in a WebView which could contain untrusted content.
• JavaScript interacts with Java object on a private, background thread of this WebView. Care is therefore required to maintain thread safety.
• The Java object‘s fields are not accessible.

Parameters

object	the Java object to inject into this WebView‘s JavaScript context. Null values are ignored.
name	the name used to expose the object in JavaScript